What is the "shortest processing time" productivity method?

Aug 02, 2022

Table of contents:

1. How does the “shortest processing time” productivity method work?
2. What is the sum of completion times?
3. What are the benefits of prioritising your tasks by duration?
4. What are the negatives of prioritising your tasks by duration?
5. When should you prioritise your tasks by duration?
6. When should you not prioritise your tasks by duration

There are many different ways to sort and prioritise your to-do list. For example, you might want to prioritise your tasks by the earliest due date so that you work on tasks that are due first. Or perhaps you want to prioritise by the eisenhower matrix to ensure you are working on your most important tasks first.

However, if you’re feeling overwhelmed by a burgeoning to-do list, sometimes you just want to get as much stuff done as quickly as possible. This is known as the “shortest processing time” method because you are prioritising tasks by how quickly they can be completed.

In this article we’ll be looking at the “shortest processing time” method, its positives, negatives, and when it would be a good choice to make the most of your productivity.

How does the “shortest processing time” productivity method work?

The “shortest processing time” method is a really simple productivity method. You basically just sort your tasks by how long they are going to take, with the quickest at the top of the list. This means you will tackle the task that will take the longest last.

If you are the only person working on this particular set of tasks, it will always take the same amount of time for you to complete the entire list no matter what order you do them in.

However, by sorting them by their duration and working on the quickest tasks first, you potentially minimise the amount of time an external resource is waiting. For example, if a colleague or team member is waiting for you to complete certain tasks so that they can continue with their work. This is known as the sum of completion times.

What is the sum of completion times?

Imagine you’re a freelance web developer and you’re currently working on two projects for a client. One project is integrating a new payment process and billing system and you expect it’s going to take 4 days. The other project is making some design changes based on their new branding, which you expect will only take 1 day.

If you work on the 4 day project first, you will deliver the work to the client on Thursday, and then you will be able to deliver the 1 day project on Friday. It took 4 days to deliver the first project, and 5 days (4 days waiting and 1 day of implementation) to deliver the 1 day project for a total of 9 days.

However, if you do the 1 day project on Monday, and then the 4 day project on Tuesday, ending on Friday, you get a very different result. In this scenario, the client has waited 1 day + 4 days for all of the work to be delivered for a total of 5 days.

In both cases, the amount of work was exactly the same to you, but by prioritising quick tasks first, you ended up saving your client 3 days of waiting for you to deliver work. This could mean the difference between that client launching their new ecommerce website on time, or blowing past the deadline.

Calculating how long it will take to complete all of the tasks is known as the sum of the completion times. As you can see in the example above, you can get very different outcomes depending on how you prioritise your tasks. If you want to minimise the sum of the completion times, a very simple solution is to use the “shortest processing time” productivity method.

What are the benefits of prioritising your tasks by duration?

The most obvious benefit of prioritising your tasks by duration and completing the quickest tasks first is that your to-do list will go down quicker. This can be particularly important if you’re currently facing an overwhelming amount of things to do.

Giving yourself some breathing space by tackling lots of small tasks will guve you the room you need to concentrate on the bigger, more important things you need to do.

Completing lots of tasks also provides you with a feeling of accomplishment. Everyone needs a dopamine hit from time to time, even if completing those small tasks isn’t really pushing you closer to your goals, the sense of accomplishment can help increase your motivation to complete tasks that don’t always have such an immediate gratification.

What are the negatives of prioritising your tasks by duration?

Whilst there are some compelling positives of prioritising your tasks by “shortest processing time”, you have to also consider the negatives.

If you are always working on quick tasks as a priority, it can mean that tasks that have a longer duration will get stuck as new tasks jump up the queue. This can mean that tasks that are expected to take longer will likely get neglected.

Unfortunately, tasks that have a longer duration are typically more complex, and are often more important in the grand scheme of things. Whilst completing smaller, less important tasks can be great for your morale, it’s all going to come crashing down when you realise you’ve been neglecting those tricky tasks that are actually going to move you close to your longer term goals.

When should you prioritise your tasks by duration?

The “shortest processing time” method is the optimal way of getting things done. This is why it’s the recommended approach of the Getting Things Done (GTD) method. This method minimises the sum of completion times, which means that if anyone is waiting on you to complete the tasks, they will be waiting for the minimum amount of time.

If you are the only person working on a set of tasks, there’s no way to change the total amount of time that you are going to be spending on completing those tasks. However, using the “shortest processing time” method will mean you get more off your plate quicker and you will be shrinking the number of outstanding tasks as quickly as possible.

Even if you’re not aware of it, you might already be using the “shortest processing time” method in your day-to-day life. I’m sure we’ve all felt that feeling of being overwhelmed with a long to-do list, and so you pick off some easy, quick tasks first to give yourself the dopamine hit you need to tackle those bigger tasks.

Or perhaps you hate the sight of unread messages, or notifications in your email or task management applications. By showing you this metric, the application is forcing you to process these items using the “shortest processing time” method. You end up going through the items, and dealing with all the easy stuff to shorten the list and make the notification badges disappear, all whilst neglecting the most important stuff that is buried in the list.

When should you not prioritise your tasks by duration

Prioritising your taks by duration only really works in either short bursts or when your workload fits a specific set of characteristics.

There’s no shame in prioritising quick tasks for short periods of time when you’re feeling overwhelmed or you don’t have the motivation to tackle bigger projects. So, having this methodology as a proven way to tackle this situation should be in every knowledge worker’s arsenal of techniques to get the most done.

However, choosing this method and sticking with it only really works when the list of tasks all have the same, or similar importance. If this is not the case, you end up with tasks that are potentially more important (and therefore have a longer duration) getting stuck. This could mean you complete all of your admin work to the detriment of working on the creative or complex projects that mean you get paid for your effort.